U.S. patent application number 11/994521 was filed with the patent office on 2009-01-29 for pressure relief valve for a battery charger.
Invention is credited to Vijay Sharan, Florin Vantu.
Application Number | 20090027004 11/994521 |
Document ID | / |
Family ID | 43402076 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090027004 |
Kind Code |
A1 |
Vantu; Florin ; et
al. |
January 29, 2009 |
PRESSURE RELIEF VALVE FOR A BATTERY CHARGER
Abstract
A battery charger (10) comprising a housing (15) enclosing
battery charging electronics (11), an interface (12) connectable to
a mains outlet, and a charging current output interface. An
aperture (71) is formed in a wall (75) of the housing, and a
pressure relief valve (90) is arranged in said aperture,
functioning to open and evacuate gas from the interior of the
housing to the exterior of the housing when the pressure in the
housing exceeds a pressure limit relative the exterior of the
housing. In one embodiment, a bushing (90) for a cable (80)
interconnecting the battery charging electronics (11) and the
charging current output interface acts as the valve.
Inventors: |
Vantu; Florin; (Malmo,
SE) ; Sharan; Vijay; (Malmo, SE) |
Correspondence
Address: |
WARREN A. SKLAR (SOER);RENNER, OTTO, BOISSELLE & SKLAR, LLP
1621 EUCLID AVENUE, 19TH FLOOR
CLEVELAND
OH
44115
US
|
Family ID: |
43402076 |
Appl. No.: |
11/994521 |
Filed: |
May 31, 2006 |
PCT Filed: |
May 31, 2006 |
PCT NO: |
PCT/EP2006/062778 |
371 Date: |
September 12, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60735155 |
Nov 9, 2005 |
|
|
|
Current U.S.
Class: |
320/111 ;
320/107 |
Current CPC
Class: |
H02J 7/0042
20130101 |
Class at
Publication: |
320/111 ;
320/107 |
International
Class: |
H02J 7/02 20060101
H02J007/02; H02J 7/00 20060101 H02J007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 5, 2005 |
EP |
05106100.0 |
Sep 27, 2005 |
EP |
05108912.6 |
Claims
1. A battery charger comprising a housing enclosing battery
charging electronics, an interface connectable to a mains outlet,
and a charging current output interface, wherein an aperture is
formed in a wall of the housing, and in that a pressure relief
valve is arranged in said aperture, functioning to open and
evacuate gas from the interior of the housing to the exterior of
the housing when the pressure in the housing exceeds a pressure
limit relative the exterior of the housing.
2. The battery charger according to claim 1, wherein the pressure
relief valve is biased to its closed state, such that the charger
will be closed after evacuation of gas from inside the housing.
3. The battery charger according to claim 1, wherein the valve
comprises a resilient member plugged into the aperture, having a
lip (93) resting against an outer surface of the housing wall and
being adapted to yield when the pressure in the housing exceeds the
pressure limit.
4. The battery charger according to claim 3, wherein an inner
surface of the lip is in communicative connection with the interior
of the housing.
5. The battery charger according to claim 3, wherein the resilient
member has an inner flange resting against an inner surface of the
housing wall.
6. The battery charger according to claim 5, wherein a portion of
the resilient member is absent from an inner flange, thereby
allowing communicative connection from the interior of the housing
to the lip.
7. The battery charger according to claim 5, wherein the resilient
member comprises, interior of the lip, an outer shoulder shaped to
abut the housing wall outside of the aperture in, said aperture
being generally circular but having a cut to the interior of the
housing extending beyond (Di) the diameter (di) of the inner flange
to permit gas through the aperture.
8. The battery charger according to claim 7, wherein a recess is
formed in the outer surface of the housing wall outwardly of the
cut, forming a pressure chamber inside the outer flange.
9. The battery charger according to claim 3, wherein the lip abuts
a recess formed in the outer surface of the housing wall.
10. The battery charger according to claim 1, wherein the pressure
relief valve acts as even as a bushing for a cable connected to the
battery charging electronics.
11. The battery charger according to claim 10, wherein the cable
has a DC charging current output connector located at a free end
remote from the housing.
12. The battery charger according to claim 10, wherein the cable
has an AC charging current input connector located at a free end
remote from the housing.
13. The battery charger according to claim 1, wherein the charging
current output interface comprises a connector shaped to be
connectable to a battery charger input port of a mobile phone.
14. The battery charger according to claim 1, wherein the housing
comprises at least two housing parts connected at a seam, and in
that the aperture extends through said seam.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of battery
chargers, specifically chargers connectable between a mains outlet
and a battery or battery-carrying electronic device, thereby
functioning to receive an AC current from the mains outlet, convert
the AC current to a DC current, and supply the DC current to the
battery for charging the same. In particular, the invention relates
to a solution for relief of a gas pressure inside a housing of an
airtight charger.
BACKGROUND OF THE INVENTION
[0002] An electronic device needs some form of electric power
supply to work. For many electronic devices, particularly portable
devices, batteries are preferred over a cord-connection to a mains
outlet. While it is possible to change batteries to a fresh set
when the charge has drained, it is common practice in many cases to
instead make use of re-chargeable batteries. Such batteries may be
re-charged using a battery charger connected to a mains outlet.
[0003] A battery charger therefore typically includes an interface
including a plug connectable to a mains outlet, AC/DC converter
electronics arranged in a protective housing, from which housing
the plug projects, and a battery interface comprising a connector
exterior of the housing. The plug is connected to the AC/DC
converter means in the housing for supplying an AC current thereto,
and the AC/DC converter means are in turn connected to the battery
connector for supplying a DC charging current to a connected
battery. The AC/DC converter electronics may be more or less
advanced, and may e.g. include a control unit for implementing a
predetermined charging scheme adapted to a certain type of battery.
In many cases, though, the actual charging control circuitry is
instead included in a device carrying the battery, such as a mobile
phone, to which device the battery connector is connected. In such
solutions, the battery charger is a fairly simple device. The
battery interface can include a battery connector comprising a plug
or socket for direct attachment of the battery or battery-carrying
device, or include a cord having such a plug or socket at its
remote free end.
[0004] For many electronic devices, a battery charger is supplied
when the device is purchased, or may be provided separately.
Furthermore, many types of electronic devices and chargers are
produced for a global market with little or no difference between
different regions or countries. The battery charger is therefore
generally a low cost product produced in millions of units, and
often supplied all over the world for use in places with varying
mains voltage. Battery chargers are also often totally insulated
products, for the purpose of avoiding humidity on the converter
electronics.
[0005] However, in some parts of the world it is more or less
common with an irregular, uneven mains voltage, which in extreme
conditions may cause a rapid development of heat and gas production
inside the charger. This process may be almost instantaneous and
the developed gases may not escape out quickly enough from the
housing of the charger. Since chargers are often provided for use
with portable devices, such as mobile phones, laptop computers,
pocket computers and so on, also the chargers are preferably very
small for good portability. Furthermore, the smaller the charger,
the smaller the space defined within its housing, which tends to
result in an even more rapid increase in pressure due to the small
enclosed volume. In serious cases, this may lead to a risk of
explosion in the charger with subsequent damage to the charger
equipment.
SUMMARY OF THE INVENTION
[0006] The object behind the present invention is therefore to
provide a solution for battery chargers, aimed to prevent the
chargers from exploding even if gas--in abnormal conditions--starts
building up pressure in the unit.
[0007] This object is fulfilled by a battery charger comprising a
housing enclosing battery charging electronics, an interface
connectable to a mains outlet, and a charging current output
interface, wherein an aperture is formed in a wall of the housing,
and in that a pressure relief valve is arranged in said aperture,
functioning to open and evacuate gas from the interior of the
housing to the exterior of the housing when the pressure in the
housing exceeds a pressure limit relative the exterior of the
housing.
[0008] In one embodiment, the pressure relief valve is biased to
its closed state, such that the charger will be closed after
evacuation of gas from inside the housing.
[0009] In one embodiment, the valve comprises a resilient member
plugged into the aperture, having a lip resting against an outer
surface of the housing wall and being adapted to yield when the
pressure in the housing exceeds the pressure limit.
[0010] In one embodiment, an inner surface of the lip is in
communicative connection with the interior of the housing.
[0011] In one embodiment, the resilient member has an inner flange
resting against an inner surface of the housing wall.
[0012] In one embodiment, a portion of the resilient member is
absent from an inner flange, thereby allowing communicative
connection from the interior of the housing to the lip.
[0013] In one embodiment, the resilient member comprises, interior
of the lip, an outer shoulder shaped to abut the housing wall
outside of the aperture in, said aperture being generally circular
but having a cut to the interior of the housing extending beyond
the diameter of the inner flange to permit gas through the
aperture.
[0014] In one embodiment, a recess is formed in the outer surface
of the housing wall outwardly of the cut, forming a pressure
chamber inside the outer flange.
[0015] In one embodiment, the lip abuts a recess formed in the
outer surface of the housing wall.
[0016] In one embodiment, the pressure relief valve acts as even as
a bushing for a cable connected to the battery charging
electronics.
[0017] In one embodiment, the cable has a DC charging current
output connector located at a free end remote from the housing.
[0018] In one embodiment, the cable has an AC charging current
input connector located at a free end remote from the housing.
[0019] In one embodiment, the charging current output interface
comprises a connector shaped to be connectable to a battery charger
input port of a mobile phone.
[0020] In one embodiment, the housing comprises at least two
housing parts connected at a seam, and the aperture extends through
said seam.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Various embodiments of the invention are described below by
means of examples with reference to the appended drawings, on
which
[0022] FIG. 1 schematically illustrates a battery charger according
to a first embodiment as seen from below;
[0023] FIG. 2 illustrates the charger of FIG. 1 from a side
view;
[0024] FIG. 3 is a transverse cross-sectional view of a portion of
the charger showing a pressure releasing device according to the
first embodiment;
[0025] FIG. 4 illustrates a close-up and partly exploded view of
the pressure releasing device of FIG. 3;
[0026] FIGS. 5 and 6 illustrate a longitudinal cross-sectional view
of the pressure releasing device according to two alternative
solutions of the first embodiment;
[0027] FIGS. 7 and 8 illustrate different views of a housing for a
charger devised according to a second embodiment of the
invention;
[0028] FIGS. 9 and 10 illustrates schematically how a cable support
member is devised to cooperate with a shaped aperture in the
housing for providing a pressure releasing device in accordance
with the second embodiment;
[0029] FIG. 11 illustrates an embodiment of a charger with a DC
cable;
[0030] FIG. 12 illustrates an embodiment of a charger with an AC
cable;
[0031] FIG. 13 illustrates an embodiment of a charger with both a
DC cable and an AC cable; and
[0032] FIG. 14 illustrates an embodiment of a charger with no
cables.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0033] The present description relates to the field of battery
chargers, particularly battery chargers adapted to charge batteries
for portable or handheld devices, such as mobile phones,
communicators, electronic organisers, smart phones, PDA:s (Personal
Digital Assistants), laptop computers etc. It should be noted,
though, that the chargers according to the invention is as such not
restricted to use with portable electronic devices. Furthermore, it
should be emphasised that the term comprising or comprises, when
used in this description and in the appended claims to indicate
included features, elements or steps, is in no way to be
interpreted as excluding the presence of other features elements or
steps than those expressly stated.
[0034] Exemplary embodiments will now be described with references
made to the accompanying drawings.
[0035] From a design point of view, a battery charger comprises the
following parts: [0036] electronic circuits, enclosed in a [0037]
plastic casing or housing, [0038] a mains interface, typically a
plug with AC pins to be inserted in a wall socket, and [0039] an
output interface, typically a connector-fitted DC cable, for
connecting the charger to a battery or battery-carrying device.
[0040] Apart from the above state of the art features, the charger
according to the invention further includes a Pressure Releasing
Device (PRD) feature, which is adapted to: [0041] quickly release
gases from the housing, in a controlled way and at a predetermined
pressure, [0042] not allow development of higher, hazardous
pressure in the charger, [0043] protect against humidity, since the
PRD will close again after releasing the pressure, [0044] prevent
external contact with the internal electronic circuits, even when
the PRD has reacted.
[0045] Preferably, the charger remains closed even after an event
has occurred which triggered the PRD to open and release the
pressure. This is an advantageous feature, preventing access to
sensitive electronics and avoiding humidity to enter the
housing.
[0046] A first embodiment of the invention is shown in FIGS. 1-6,
in which the PRD by way of example is incorporated in resilient
grip pads, normally made in a rubber-like resilient material. In
FIG. 1, a battery charger 10 is shown. Charger 10 comprises
electronic circuits 11 for converting an AC voltage to a DC
voltage, according to the established art. The electronic circuits
11 are connected to a mains outlet connector 12. In this particular
embodiment the mains outlet connector comprises two parallel and
spaced apart pins 12 extending from a spacer element 13, devised to
connect to a mains outlet socket. However, it is well known that
there are other designs for the mains outlet interface used in
various countries, and it should be noted that the invention is in
no way restricted to the illustrated example. The mains outlet
connector may in fact even comprise a socket instead of a plug, for
connection to a mains outlet plug. The electronic circuits 11 are
further connected to a charging current output connector 18 via a
DC cable 14. A casing or housing 15 encloses the electronic
circuits 11, and a bushing is provided to support the cable at its
connection to housing 15. FIG. 1 further indicates two pressure
release devices PRD 20, but it should be noted that only one may
suffice or that more than two may be included. The pressure
releasing device comprises an aperture leading to a volume or
cavity defined in the interior of the housing, and a valve placed
in the aperture.
[0047] In FIG. 2, charger 10 is depicted from the side, and from
this drawing it is evident that housing 15 comprises at least two
housing parts 15a and 15b, which are fixed to each other by a seam
16 by welding, gluing, snap-locking, screwing, or any other
affixation method. In this embodiment, the PRD 20 comprises a plug
21 acting as the valve, formed of a resilient material such as e.g.
rubber, silicone or thermo-elastic plastic, and placed in an
aperture 30 formed in housing 15. As is evident from FIG. 2, the
body 21 is preferably located in the seam 16, for easy mounting
during manufacture. An alternative variant is to form the aperture
without passing the seam, and subsequently pressing the resilient
body into place.
[0048] In one embodiment, the valve may comprise a rigid or
resilient body, which is spring-loaded towards a valve seat defined
in or outside a rim defining the aperture. Preferably, though, the
body comprises in itself a resilient or elastic portion providing
the valve function, as is explained below.
[0049] FIG. 3 schematically illustrates a cross-sectional view
through A-A as shown in FIG. 2, from which it is clear how body 21
is placed in aperture 30. In this embodiment and in this
orientation, body 21 comprises an outer flange or lip 22 abutting
against a surface of an outer wall of housing 15, an inner flange
24 abutting against a surface of an inside wall of housing 15, and
a central portion 23 being narrower than and connecting the two
flanges.
[0050] However, in order for an over pressure to be eliminated by
gas evacuation, there has to be gas communication from the interior
to the exterior of housing 15. For this purpose, the inner flange
is shaped such that it is present only at certain portions about
the inner periphery of aperture 30, and absent at another portion.
This is schematically illustrated in FIGS. 4-6. FIG. 4 illustrates
body 21 present between two housing parts 15a and 15b before
assembly. Aperture 30 is thus not yet formed, but its boundaries
are formed at edge portions 30a and 30b in the housing parts 15a
and 15b, respectively. From the drawings it is clear that outer
flange 22 has a (oval) shape which more or less corresponds to that
of aperture 30, but which extends beyond the periphery of aperture
30 to seal the same. Central portion 23 is smaller than aperture
30, in order to provide gas communication between the housing edge
of the aperture 30 and the central portion 23. However, the inner
flange 24 has a shape which deviates from the aperture 30, in that
flange 24 extends beyond the edge 30a, 30b of aperture 30 at the
longitudinal sides, to the left and right in the drawing, but not
at the shorter ends, i.e. the upper and lower ends in the drawing.
At those shorter ends gas may consequently flow freely towards an
inner surface 25 of outer flange 22 to expose it to pressure. FIG.
5 illustrates a cross-sectional side view through B-B indicated in
FIG. 4, from which it is clear how the outer flange 22 rests
against the outside of housing wall 15, and that inner surface 25
of the outer flange is exposed to the gas pressure interior of the
housing. FIG. 6 illustrates, by way of example, a modified version
of this embodiment, in which flange 22 is positioned in a recess 17
in the housing, in order to make it more difficult to tamper with
the charger to lift or even remove the body 21.
[0051] FIGS. 7-10 illustrate by way of example a second embodiment
of the invention. In this embodiment, the PRD is incorporated in a
strain relief bushing on a cable connected to the housing of the
charger, such as a DC cable for the output connector or an AC cable
for the mains connector. This way the PRD function is built-in
without any substantial additional costs, if the strain relief
bushing is fitted to the cable in question anyway. In the
illustrated example, the pressure relief device is incorporated in
the DC cable.
[0052] FIGS. 7 and 8 illustrate a housing 70 for a battery charger.
A mains plug is illustrated, whereas the electronic circuits are
left out. Housing 70 has an aperture 71 shaped in a seam 76 between
two housing parts 70a and 70b. Normally the housing parts are
assembled via ultrasonic welding, but other methods are possible as
mentioned above. For easy insertion, the cable with the special
strain relief including the pressure releasing device is preferably
located in the parting plane between top and bottom part of the
charger housing.
[0053] Aperture 71 has a special shape which will be outlined in
detail, and is also used for leading a cable between the charging
electronics inside housing 70 and the charging current connector
located at the far end of the cable (not shown).
[0054] FIG. 10 shows a cross-section of the housing 70 with
aperture 71 in housing wall 72, through which a cable 80 is let
through. Cable 80 is attached by means of a bushing 90 for the
cable being clamped in the aperture. This bushing has a particular
design and acts as the valve in accordance with this embodiment of
the invention. Cable 80 is preferably integrated with or securely
attached in a through-bore 94 of bushing 90. One alternative is to
use a bushing which is over-moulded on the cable. In FIG. 10, the
left side of housing wall 72 represents the interior of the housing
70 and the right side of housing wall 72 represents the exterior of
the housing 70.
[0055] In FIG. 9 aperture 71 is seen from the front as in FIG. 7,
but also with some diameters of bushing 90 shown with dashed lines.
Aperture 71 is in the shown embodiment generally circular with a
diameter hd. However, other shapes of the bushing middle part which
secure the cable against rotation may be preferred, such as
triangular, rectangular or other polygonal shape. In this sense,
the word diameter is still used to denote an outermost perimeter
from a central point or axis.
[0056] Inside the housing 70, bushing 90 abuts with an inner flange
91 having a diameter di. At the exterior of the aperture 71 the
bushing 90 has a shoulder 92 with a diameter d. As is seen in FIGS.
7-10 the aperture 71 is not completely circular but is provided
with a cut 73 and a recess 74. The cut 73 has a dimension Di
greater than di. Thus, the inner flange 91 does not cover the
entire aperture but there is an air-escape way through the cut 73
leading to the recess 74, which forms a pressure chamber at the
exterior side of the wall 72. The pressure chamber 74 extends to a
dimension D. This recess 74 might be very ground, typically between
0.05-1 mm, and preferably between 0.1 and 0.5 mm, e.g. about 0.2
mm, but its existence provides an advantageous contribution for
obtaining an improved function. Between this inner wall of the
recess and the external lip 93 the pressure chamber 74 formed,
which is in permanent connection with the space in the charger
body, via the cut 73. The surface of the recess and the yieldable
lip's pre-tension and material's properties are elements which may
be designed to determine the opening pressure for the pressure
relief valve function.
[0057] The pressure chamber 74 is closed by outer flange or lip 93
of bushing 90. The outer flange 93 is preferably accommodated
inside a further shoulder 75 on the exterior surface of the housing
1. The diameter of the outer flange 93 is LD which is greater than
the dimension D of the pressure chamber. The bushing 90 is
preferably made of any of the aforementioned elastic materials.
When the pressure in the pressure chamber 74 exceeds a limit the
outer flange will yield to evacuate gases from the pressure chamber
74 to the outside of the housing. In this way, the bushing 90 with
the lip 93 provides pressure relief for the housing 70 via the air
escape way through the cut 73, the pressure chamber 74 and the
yieldable lip 93. The valve function achieved is biased to its
closed position, by means of the shape and resiliency of the
bushing 90. The same goes for the embodiment of FIGS. 1-6, where it
is the shape and resiliency of body 21 which guarantees the one-way
function of the valve.
[0058] The most common embodiment of a battery charger is to employ
a housing carrying the converter electronics and a mains plug,
whereas the DC connector is fitted to the far end of a cable
connected to the electronics in the housing, which is the design
presented in the embodiments of FIGS. 1-10. It should be noted,
though, that alternative embodiments are possible, as is explained
with reference to FIGS. 11-14. The mains plug, for one thing, may
also be connected to a remote end of an AC cable attached to the
housing. Likewise, the DC connector may be fitted directly on the
housing. A charger according to the invention may thus comprise no
cables, one AC cable, one DC cable, or one AC cable and one DC
cable. Furthermore, the mains plug exists in different shapes,
making the charger country- or region-dedicated.
[0059] FIG. 11 shows a design corresponding to the previous
drawings, with a charger housing 112 containing the charging
converter electronics, a mains plug 113 fitted on housing 112, for
connection to a mains outlet 111. Housing 112 is also fitted with a
DC output cable 114 carrying a DC connector 115 at its remote end,
for connection to a socket 116 of a battery or battery-carrying
device 117.
[0060] FIG. 12 illustrates a first alternative design, where
charger housing 112 containing the charging converter electronics
is connected to mains plug 113 via an AC cable 118, for connection
to mains outlet 111. Housing 112 is fitted with a DC connector 115
and preferably some form of socket for securely attaching battery
or device 117 with its socket 116.
[0061] FIG. 13 illustrates a second alternative design, where
charger housing 112 containing the charging converter electronics
is connected to mains plug 113 via an AC cable 118, for connection
to mains outlet 111, and to a DC output cable 114 carrying a DC
connector 115 at its remote end, for connection to a socket 116 of
a battery or battery-carrying device 117.
[0062] FIG. 14 illustrates a third alternative design, where both
mains plug 113 for connection to mains outlet 111 and DC connector
115 for connection to socket 116 of battery or device 117, are
directly fitted on housing 112.
[0063] As previously mentioned, battery-carrying device 117 may
e.g. be a mobile phone, a communicator, an electronic organiser, a
PDA, or a laptop computer. Further alternatives include a camera, a
media player such as a DVD or mp3 player, electronic toys, and so
on.
[0064] The invention has been described by means of reference to
examples of embodiments, but it be understood that variations
within the scope of the appended claims are plausible. Certain
elements have been described in more or less detail even though the
actual realisation of those elements are of little or no importance
to the invention. For instance, the mains plug need not be located
to extend at an angle from a charging cable, but may instead extend
in the opposite direction of the cable. The seam provided between
two housing parts, if at all present, may just as well be provided
through e.g. a longitudinal plane in FIG. 7, or have an irregular
shape. Furthermore, a charger completely without cable is also
possible, provided there is a connector for attaching a battery or
battery-carrying device. It should also be noted that the feature
of combining the cable bushing with the valve body as described in
conjunction with FIGS. 7-10, could just as well be implemented for
the embodiment described with reference to FIGS. 1-6.
* * * * *